9,279 research outputs found
Electron generation of leptons and hadrons with reciprocal alpha-quantized lifetimes and masses
Hadron elementary particle measurements have long revealed an
alpha-dependence in the long-lived threshold-state lifetimes, together with an
alpha-related mass structure, where alpha ~ 1/137 is the fine structure
constant. A detailed lifetime analysis shows that of the 156 particles with
well-determined lifetimes, the 120 shortest lifetimes have a continuum of
values, but the 36 longer lifetimes occur in alpha-spaced groups which are
sorted into s, c, b quark flavors. Guided by these lifetime results, we deduce
an alpha-generated set of universal mass quanta, based on the electron ground
state, which apply to both leptons and hadrons. A low-mass "threshold-state
octet" of particles - muon, proton, tau, pion, eta, eta prime, kaon, phi meson
- is reproduced to an average mass accuracy of 0.4%, with no adjustable
parameters except a small hadronic binding energy. Without the lepton states,
the hadron mass pattern is difficult to ascertain.Comment: 106 pages, 33 figures, invited review articl
Spin Ice, Fractionalization and Topological Order
The spin ice compounds {\dys} and {\holm} are highly unusual magnets which
epitomize a set of concepts of great interest in modern condensed matter
physics: their low-energy physics exhibits an emergent gauge field and their
excitations are magnetic monopoles which arise from the fractionalization of
the microscopic magnetic spin degrees of freedom. In this review, we provide an
elementary introduction to these concepts and we survey the thermodynamics,
statics and dynamics---in and out of equilibrium---of spin ice from these
vantage points. Along the way, we touch on topics such as emergent Coulomb
plasmas, observable "Dirac strings", and irrational charges. We close with the
outlook for these unique materials.Comment: (15 pages, 9 figures) see
http://www.annualreviews.org/doi/abs/10.1146/annurev-conmatphys-020911-125058
for the published versio
MgB2 radio-frequency superconducting quantum interference device prepared by atomic force microscope lithography
A new method of preparation of radio-frequency superconducting quantum
interference devices on MgB2 thin films is presented. The variable-thickness
bridge was prepared by a combination of optical lithography and of the
scratching by an atomic force microscope. The critical current of the
nanobridge was 0.35 uA at 4.2 K. Non-contact measurements of the current-phase
characteristics and of the critical current vs. temperature have been
investigated on our structures.Comment: RevTeX4. Accepted in Appl. Phys. Let
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